Embodiments of the inventive concept disclosed herein relate to an electronic circuit, and, more particularly, to an image sensor.
An image sensor may include an electronic circuit for sensing light. Image sensors are used in electronic devices, such as cameras, scanners, and/or smartphones. An image sensor may include a charge coupled device (CCD) image sensor and a complementary metal-oxide semiconductor (CMOS) image sensor (CIS). There is an increasing demand for CMOS image sensors for use in smartphone cameras.
A CMOS image sensor may include unit pixels implemented with CMOS transistors. A CMOS image sensor may use photo diodes included in the unit pixels to sense light. A photo diode absorbs light energy, generating electron-hole pairs (EHPs). Transistors included in a pixel convert charges generated by the photo diode to a voltage signal. The CMOS image sensor obtains information about light energy sensed by unit pixels by using voltage signals generated in the unit pixels.
Because the unit pixels of a CMOS image sensor are manufactured using fine processes, noise due to coupling may occur. A smear, such as horizontal noise (SHBN), is noise occurring in the CMOS image sensor. SHBN means noise corresponding to a fixed horizontal pattern due to coupling between adjacent pixels. For example, in the case where an image sensor senses a bright light source in a low-illuminance environment, an image including a fixed, band shape pattern may be output.